Labour's 1940s chancellor Sir Stafford Cripps, ferociously abstinent and ascetic in his private habits, was the ideal man to preach public restraint in the postwar years. But his lesson, that if you wish to promote public austerity then the message comes best from someone of unimpeachable personal frugality, has been lost on David Cameron. In almost every respect, Sir Philip Green, appointed this week to carry out an external review of public spending cuts, is the antithesis of Cripps. Though he may run a tight ship in his businesses, in private Sir Philip is a hedonistic voluptuary, whose permatanned corpulence bears witness to his lifestyle as accurately as Cripps's own skeletal physique did in the 1940s.

Sir Philip is also – we must express this with care – a man who is careful to arrange his own finances so as not to needlessly benefit the common weal. In 2005, for example, the man whom Robert Peston dubs both a lovable rogue and the king of jackpot capitalism paid himself a tax-free dividend of £1.2bn from the Arcadia retailing business. Technically the dividend went to his Monaco-resident wife, in order to avoid UK Treasury attention, a tax saving to Sir Philip that has been estimated at £300m. That one dividend payment, as Mr Peston has written, was equivalent to what 54,000 people on average earnings would earn in a year, would build around 10 secondary schools capable of educating some 13,000 young people, or, if paid in an unlikely column of pound coins, would tower 2,350 miles about the Earth's surface.

If Sir Philip can come up with useful economies for the exchequer that no one else has identified then, perhaps, well and good. But in most respects the whole exercise, due to last less than two months – and thus exactly the kind of short-term "three-, six-, 10-week hype" with which Sir Philip used to say he would have nothing to do – smells of a fishiness that deserves to cling to the ministers who dreamed it up and which will hopefully do the government no credit at all with the taxpaying public. All in this together? Not Sir Philip and his wife. His role sends a deplorable and very powerful signal about the government's fiscal values.